This invention relates to devices for detecting sound pressure levels such as may be useful for monitoring noise levels in varying environments, particularly with respect to mobile monitoring of automotive and truck noise levels by law enforcement agencies.
While vehicle mounted speed detectors based on radar principles are relatively well known and are commonly used by law enforcement officials, the need to monitor vehicular noise levels in an analogous way has, until recently, been mostly conjectural. Devices adapted to monitor sound pressure levels have heretofore been complex, difficult to operate and expensive, and have been designed for precision laboratory use, where precise tolerances, multiple scales, variable frequency responses, meter response times are desired. Such devices have been found to be unsuitable for law enforcement applications, not only due to their complexity and attendant expense, but also because they have failed to provide features of appreciable importance in that area of use.